Spinous process plate fixation assembly

ABSTRACT

A spinous process plate fixation assembly is provided that has a pin plate including a first central aperture and a pin plate interior surface. The assembly has a lock plate including a second central aperture and a lock plate interior surface opposingly facing the pin plate interior surface. The interior surfaces have a pluralities of spikes extending therefrom. A pin receptacle is disposed within the pin plate and is configured to receive a lock pin. A pivoting lock mechanism is disposed within the lock plate. A connector shaft extends from the pin plate to the lock plate and passes through the first central aperture and the second central aperture. The connector shaft includes a pin side configured to receive the lock pin, and a lock side opposite the shaft side, the lock side configured to operatively engage the pivoting lock mechanism so as to secure the plates and the shaft.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a nonprovisional patent application claimingthe benefit of the priority dates from U.S. Provisional Application No.62/272,618, filed on Dec. 29, 2015, and U.S. Provisional Application No.62/273,350, filed on Dec. 30, 2015, the entire contents of which arehereby expressly incorporated by reference into this disclosure as ifset forth fully herein

FIELD

The present disclosure relates generally to medical devices, morespecifically to the field of spinal surgery and devices for fusingadjacent spinous processes to stabilize the vertebral segment associatedwith the particular spinous processes. Such devices as well as systemsand methods for use therewith are described.

BACKGROUND

The spinal column is critical in human physiology for mobility, support,and balance. The spine column protects the nerves of the spinal cord,which convey commands from the brain to the rest of the body, and conveysensory information from the nerves below the neck to the brain. Thespinal column is made of two basic components—vertebrae (bone) andintervertebral discs (gel-like cushions that absorb pressure and preventvertebrae from rubbing together). A number of vertebrae andintervertebral discs stack together to form a column that providessupport and structure for the body while still allowing a large degreeof motion and flexibility and protecting the spinal cord. Even minorspinal injuries can be debilitating to the patient, and major spinalinjuries can be catastrophic. The loss of the ability to bear weight orpermit flexibility can immobilize the patient. Even in less severecases, small irregularities in the spine can put pressure on the nervesconnected to the spinal cord, causing devastating pain and loss ofcoordination. Examples of causes of such pain include changes in discheight and improper motion of vertebrae.

Surgical procedures on the spine often include the immobilization of twoor more vertebrae, typically by fusing vertebrae together. As a resultof such surgical invention, disc height may be corrected, and vertebraemay be immobilized, while fusion occurs.

One of the more common methods for achieving the desired immobilizationis through the application of bone anchors (most often introduced intothe pedicles associated with the respective vertebrae to be fixed) thatare then connected by rigid rods locked to each pedicle screw. Asignificant challenge with such bone anchors is securing the pediclescrews without breaching, cracking, or otherwise compromising thepedicle wall, which may occur if the screw is not properly aligned withthe pedicle axis. Moreover, such pedicle screw systems require invasivesurgery. Therefore, a need continues to exist for systems for fusingvertebrae that can be used as alternatives to pedicle screws and can beused in minimally invasive surgical procedures.

SUMMARY

The needs described above, as well as others, are addressed byembodiments of a spinous process plate fixation assembly described inthis disclosure (although it is to be understood that not all needsdescribed above will necessarily be addressed by any one embodiment), asthe spinous process fixation plate assembly of the present disclosure isseparable into multiple pieces and can be assembled in-situ, and thus,can be used in minimally invasive spinal surgeries. Moreover, theassembly of the present disclosure does not rely on a pedicle screwsystem.

In an aspect, a spinous process plate fixation assembly includes a pinplate and a lock plate. The pin plate has a first central aperture and apin plate interior surface. The pin plate interior surface has a firstplurality of spikes extending therefrom. A pin receptacle is disposedwithin the pin plate and is configured to receive a lock pin. The lockplate has a second central aperture and a lock plate interior surfaceopposingly facing the pin plate interior surface. The lock plateinterior surface has a second plurality of spikes extending therefrom. Apivoting lock mechanism is disposed within the lock plate. A connectorshaft extends from the pin plate to the lock plate and passes throughthe first central aperture and the second central aperture. Theconnector shaft includes a pin side configured to receive the lock pin,and a lock side opposite the shaft side, the lock side configured tooperatively engage the pivoting lock mechanism.

In an embodiment of the spinous process plate fixation assembly, thelock mechanism includes a threaded channel disposed within a top surfaceof the lock plate and a lock chamber disposed within the lock plate. Apivoting lock is disposed within the lock chamber and includes a lockslot in communication with the threaded channel. The pivoting lockincludes a connector shaft passage configured to receive the lock sideof the connector shaft.

In an embodiment of the spinous process plate fixation assembly, each ofthe first plurality of spikes and the second plurality of spikes includespikes having cuboid-shaped bases and pyramid-shaped tips. The first andsecond pluralities of spikes may be positioned on offset flat portionsof the pin plate and the lock plate, respectively. Each of the pin plateand the lock plate may have two staggered flat portions.

The pin plate and the lock plate may each include an exterior facepositioned opposite of the pin plate interior surface and the lock plateinterior surface, respectively. Each of the exterior faces may includeat least two compressor alignment slots disposed on opposite sides ofthe connector shaft.

In another aspect, a kit comprises a lock pin and a pin plate includinga first central aperture and a shaft plate interior surface, the pinplate interior surface including a first plurality of spikes. A pinreceptacle is disposed within the pin plate and configured to receivethe lock pin. The lock plate includes a second central aperture and alock plate interior surface. The lock plate interior surface including asecond plurality of spikes. The kit includes a pivoting lock mechanismconfigured to be received in the lock plate. The kit comprises aconnector shaft configured to extend from the pin plate to the lockplate and pass through the first central aperture and the second centralaperture. The connector shaft includes a pin side configured to receivethe lock pin; and a lock side opposite the shaft side, the lock sideconfigured to operatively engage the pivoting lock mechanism.

The pivoting lock mechanism may include a threaded channel disposedwithin a top surface of the lock plate, a lock chamber disposed withinthe lock plate, and a pivoting lock disposed within the lock chamber andincluding a lock slot in communication with the threaded channel. In anembodiment, the pivoting lock includes a connector shaft passageconfigured to receive the lock side of the connector shaft. The pivotinglock may include an exterior toroidal surface and an interior frictionfit surface. In some embodiments, the kit includes a lock flangeconfigured to secure the pivoting lock within the lock chamber. Thepivoting lock may include a compression slot proximal to the lock slotand opposite from a compression flat configured for orientation when thepivoting lock is compressed. The compression slot may be configured tobe reduced when the pivoting lock is compressed.

In an embodiment of the kit, each of the pin plate and the lock plateinclude at least two staggered flat portions. Each of the pin plate andthe lock plate may include an exterior face opposite of the pin plateinterior surface and the lock plate interior surface, respectively. Eachof the exterior faces may include at least two compressor alignmentslots disposed on opposite sides of the connector shaft. The kit mayinclude an instrument selected from the group of an inserter-compressorinstrument, a shaft inserter, a single locking tool, a compressor, andcombinations thereof.

In another aspect, a midline spinal allograft includes a body having alower side opposite of an upper side. The lower side has a caudal groovedimensioned to receive a cranial side of a lower spinous process. Theupper side has a cranial groove dimensioned to receive a cranial side ofan upper spinous process. The cranial groove may have a cranial grooveheight greater than a caudal groove height of the caudal groove, and thecranial groove may have a cranial groove width greater than a caudalgroove width of the caudal groove. At least two lower legs are disposedaround the caudal groove, and at least two upper legs are disposedaround the cranial groove.

In yet another aspect, a method of producing a demineralized allograftis disclosed herein. The method includes harvesting cancellous bone,cutting the harvested cancellous bone into a predetermined block size,weighing the cut cancellous bone, determining the cut cancellous bonehas a mass density greater than a minimum mass density, shaping andsizing the cut cancellous bone to a predetermined shape and size to forma midline spinous allograft, washing the midline spinous allograft,demineralizing the midline spinous allograft in an acid, cleaning thedemineralized midline spinous allograft, and packaging the cleaneddemineralized midline spinous allograft.

The above presents a simplified summary in order to provide a basicunderstanding of some aspects of the claimed subject matter. Thissummary is not an extensive overview. It is not intended to identify keyor critical elements or to delineate the scope of the claimed subjectmatter. Its sole purpose is to present some concepts in a simplifiedform as a prelude to the more detailed description that is presentedlater.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A perspective view of an embodiment of a spinous process platefixation assembly as assembled for usage.

FIG. 2 A perspective view of the spinous process plate fixation assemblyshown in FIG. 1 when disassociated.

FIG. 3. A cross-section view of the spinous process plate fixationassembly shown in FIG. 1

FIG. 4. An exploded view of the spinous process plate fixation assemblyshown in FIG. 1.

FIG. 5. A perspective view of the pivoting lock of the spinous processplace assembly shown in FIG. 1.

FIG. 6. A lateral view of the spinous process plate fixation assemblyshown in FIG. 1 compressed to a spine in one orientation.

FIG. 7. A posterior view of the spinous process plate fixation assemblyand spine shown in

FIG. 8. A perspective view of the spinous process plate fixationassembly and spine shown in FIG. 6.

FIG. 9. A top view of the spinous process plate fixation assembly shownin FIG. 1.

FIG. 10. An alternate perspective view of the spinous process platefixation assembly shown in FIG. 1.

FIG. 11. A side view of the spinous process plate fixation assemblyshown in FIG. 1.

FIG. 12. A perspective view of a combination inserter-compressorinstrument holding an assembled spinous process plate fixation assemblyshown in FIG. 1.

FIG. 13. A perspective view of a single shaft inserter holding anassembled spinous process plate fixation assembly shown in FIG. 1.

FIG. 14A. A perspective view of a ligament sparing surgical techniqueshowing a pin plate through a ligament with a lock plate beingintroduced into the surgical site with the single shaft inserter and asingle locking tool.

FIG. 14B. A magnified view of the pin plate and the lock plate in theligament sparing surgical technique shown in FIG. 14A.

FIG. 15. A perspective view of the single shaft inserter and the singlelocking tool on the spinous process plate fixation assembly shown inFIG. 1 when using the ligament sparing surgical technique.

FIG. 16. A perspective view showing the assembly shown in FIG. 1 beingcompressed using simple compressors on a spine.

FIG. 17. A perspective view of an embodiment of a midline allograftplaced between spinous processes of adjacent lumbar vertebrae.

FIG. 18. A perspective view of the midline allograft of FIG. 17 withposterior fixation elements installed.

FIG. 19. A perspective view of an embodiment of a midline allograft.

FIG. 20. A perspective view of another embodiment of a midlineallograft.

FIG. 21A. A top view of the midline allograft of FIG. 20.

FIG. 21B. A bottom view of the midline allograft of FIG. 20.

FIG. 21C. A side view of the midline allograft of FIG. 20.

DETAILED DESCRIPTION

Illustrative embodiments of a spinous process plate fixation assemblyand midline spinous process allograft are described below. In theinterest of clarity, not all features of an actual implementation aredescribed in this specification. It will of course be appreciated thatin the development of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure. The spinous process fixation plate assembly, midlinespinous process allograft, and related methods disclosed herein boast avariety of inventive features and components that warrant patentprotection, both individually and in combination.

As used herein, the term “proximal” means the side facing closest to thesurgeon when the device is properly implanted, whereas the term “distal”means the side facing away from the surgeon.

Spinous Process Plate Fixation Assembly

A spinous process plate fixation assembly 100 is provided that includesa pin plate 102 and a lock plate 104. The pin plate 102 has a firstcentral aperture 106 disposed at, or proximate to, the center of a pinplate interior surface 108. The pin plate interior surface 108 may beflat or substantially flat. The pin plate interior surface 108 has afirst plurality of spikes 110 extending therefrom. A pin receptacle 112is disposed within the pin plate 102 and is configured to receive a lockpin 114 (FIG. 4). The pin receptacle 112 may originate in a top surface116 of the pin plate 102. The pin receptacle 112 may include a pinchamber 118 that is shaped complementarily to pin 114 such as to receivethe pin 114. The pin chamber 118 may extend vertically through the pinplate 102.

When joined in the spinous process plate fixation assembly 100 (as shownin FIG. 1), the lock plate 104 may be positioned laterally opposite ofthe pin plate 102. The lock plate 104 has a second central aperture 120disposed at, or proximate to, the center of a lock plate interiorsurface 122. The lock plate interior surface 122 opposingly faces thepin plate interior surface 108 when the assembly 100 is assembled. Thelock plate interior surface 122 has a second plurality of spikes 124extending therefrom. A pivoting lock mechanism 126 is disposed withinthe lock plate 104. The pivoting lock mechanism 126 may be in fluidcommunication with the second central aperture 120. When assembler 100is assembled, a connector shaft 128 extends from the pin plate 102 tothe lock plate 104 and passes through the first central aperture 106 andthe second central aperture 120, operatively connecting the pin plate102 and the lock plate 104, as shown in FIG. 1.

The connector shaft 128 includes a pin side 130 configured to receivethe lock pin 114, and a lock side 132 opposite the pin side 130, thelock side 132 being configured to operatively engage the pivoting lockmechanism 126. The pin side 130 may have a pin lock channel 131 disposedvertically therein that is configured to receive the lock pin 114. Thepin lock channel 131 may be shaped complementary to the lock pin 114. Inone embodiment of the assembly 100, the pin 114 is welded, or otherwisefixedly attached, to the pin plate 102 such that the pin 114 is securedwithin both of the pin lock channel 131 of the connector shaft 128 andthe pin receptacle 112 of the pin plate 102. The welding or attachmentof pin 114 fixes the connection between the pin plate 102 and theconnector shaft 128 such that the connector shaft 128 does not moverelative to the pin 114. In an alternative embodiment of the assembly100, the pin 114 is not welded or fixedly attached to the pin plate 102such that the connector shaft 128 is able to move relative to the pin114.

The lock side 132 of the connector shaft 128 may include a tapered tip133. When engaged in the lock plate assembly 100, the tapered tip 133may extend beyond the outer most surface of the lock plate 104.Advantageously, the tapered tip 133 enables user-friendly engagement fora surgeon assembling the assembly 100 in-situ. For example, the taperedtip 133 allows the surgeon to easily position the tapered tip 133 with apre-perforated ligament (not shown) or to create a perforation (notshown) using the tapered tip 133. The connector shaft 128 may have aplurality of flanges 134, which may be V-shaped, disposed on its surfacefor operatively engaging pivoting lock mechanism 126. The V-shapedflanges 134 increase friction during locking of the assembly 100 due toan interaction with the pivoting lock mechanism 126 and a lock groove156.

In an embodiment, as shown in FIGS. 3 and 4, the pivoting lock mechanism126 includes a threaded channel 136 disposed vertically through the lockplate 104 and terminating at a lock aperture 138 in a top surface 140 ofthe lock plate 104. The lock aperture 138 is open to the threadedchannel 136. A pivoting lock 142, shown in detail in FIG. 5, can bedisposed in a lock chamber 144 of the lock plate 104 when assembled (asshown in, for example, FIG. 3) as part of the pivoting lock mechanism126. The pivoting lock 142 includes a lock slot 145 that is in fluidcommunication with the threaded channel 136 of the lock plate 104 whenthe assembly 100 is assembled (FIG. 3). The pivoting lock 142 includes aconnector shaft passage 146 configured to receive the lock side 132 ofthe connector shaft 128. The pivoting lock mechanism 126 includes a lockflange 148 which is configured to be received by the lock chamber 144,the connector shaft 128, and the pivoting lock 142. When the assembly100 is assembled, as shown in FIGS. 1 and 3, the lock flange 148 securesthe pivoting lock 142 within the lock chamber 144 of the lock plate 104while allowing the pivoting lock 142 to pivot, or rotate, within thelock chamber 144.

As shown in FIG. 5, the pivoting lock 142 may have an exterior toroidalsurface 150. The exterior toroidal surface 150 may be shapedcomplementary to the lock chamber 144 so that the pivoting lock 142 canbe received and rotate within the chamber 144. The pivoting lock 142 mayhave an interior friction fit surface 152. The interior friction fitsurface 152 may be shaped complementary to the shape of the connectorshaft 128. As such, the shape of the friction fit surface 152 islaterally flat and has two arcs that continuously curve, interrupted bya compression slot 154 and the lock groove 156. The compression slot 154may be positioned proximate to the lock slot 145, and the lock groove156 may be positioned opposite of lock groove 156. Advantageously, whenthe pivoting lock 142 is compressed in use, the compression slot 154 isreduced, or pinches, to enable the pivoting lock 142 to secure theconnector shaft 128 that is disposed within the connector shaft passage146. The lock groove 156 provides flexibility in the axis of thereduction such that the compression slot 154 is reduced when verticalforce is applied in use. This force may be applied by a threaded lockingfeature 158.

The threaded locking feature 158 may have threads configured tooperatively engage with threads in the threaded channel 136 of the lockplate 104. When the threaded locking feature 158 is engaged with thethreaded channel 136, the threaded locking feature 158 travels throughthe threaded channel 136 to engage and secure the pivoting lock 142. Thethreaded locking feature 158 may have a locking tab 160 disposed on itsbase, the locking tab 160 configured to engage with the locking slot 145of the pivoting lock 142. Advantageously, when the threaded lockingfeature 158 engages and secures the pivoting lock 142, the pivoting lock142 is fixed, or secured, in a position, thereby also securing the lockside 132 of the connector shaft 128.

Advantageously, the pivoting lock mechanism 126 disclosed herein allowsthe assembly 100 to have nearly infinite variable locking positions withthe maximum positions formed by the threaded locking feature 158 and thelock plate 104. The pivoting lock mechanism 126 allows the lock plate104 to float around it prior to locking. During compression, thepivoting lock mechanism 126 allows the lock plate 104 to articulate inall directions, and then during locking secures the lock plate 104 inthe position found during compression. The compression on the pivotinglock 142 remains the same in any position.

In an embodiment of the assembly 100, each of the first plurality ofspikes 110 and the second plurality of spikes 124 include spikes havingcuboid-shaped bases 162 and pyramid-shaped tips 164 (FIGS. 9 and 10)(which can be described as “house-shaped”). Each of the first pluralityof spikes 110 and the second plurality of spikes 124 may have minor(i.e., relatively small) spikes 166 and major (i.e., relatively large)spikes 168. The house-shaped spikes of varying size increase the bite,or grip, of the spikes on vertebrae 170 of a spine 172 to be immobilizedand provide increased resistance, when engaged with the vertebrae 170,of movement, including caudal, cranial, distal, dorsal and rotational.In particular, engaged pluralities of spikes 110 and 124 provide a highlevel of torsional micro motion resistance within the bone duringflexion/extension movement. The first plurality of spikes 110 and thesecond pluralities of spikes 124 may each be positioned on a firstoffset flat portion 174 and a second offset flat portion 176,respectively, of the plates 102 and 104. Each of the pin plate 102 andthe lock plate 104 may have exactly two staggered flat portions 174 and176. The first offset flat portion 174 and the second offset flatportion 176 may be vertically offset, or staged, from one another aroundthe connector shaft 128. The first flat portion 174 may be defined by astep-down, or drop, in a bottom surface 178 in the pin plate 102 and abottom surface 180 in the lock plate 104, and a step-down, or drop inthe top surfaces 116 and 140 of the plates 102 and 104. The second flatportion 176 may be positioned opposite from the first flat portion 174.The second flat portion 176 may be defined by a step-up, or rise, in abottom surface 178 in the pin plate 102 and a bottom surface 180 in thelock plate 104, and a step-up, or rise in the top surfaces 116 and 140of the plates 102 and 104. The top surfaces 116 and 140 and the bottomsurfaces 178 and 180 are flat, or substantially flat, across the firstoffset flat portion 174 and the second offset flat portion 176.

Advantageously, assembly 100 having plates 102 and 104 with flatportions 174 and 176 has a lower profile, which is beneficial forperforming minimally invasive surgeries, and is shaped to interface withallograft and/or polyetheretherketone devices. The anterior side of theplates 102 and 104 can include a radiused section 177 configured tointeract with the allograft or a polyetheretherketone spacer. Thedimensions of the radiused section 177 allow the assembly 100 to be postpacked with autograft or allograft after full locking, as the connectorshaft 128 and the interior surfaces 108 and 122 create a barrier withwhich bone chips can easily be packed. Moreover, the lower profile ofthe disclosed assembly 100 allows the plates 102 and 104 to attachfurther on a spinous process 194 and to have the pluralities of spikes110 and 124 compressed into the transition area between the lamina andthe spinous process 194. Furthermore, this profile potentially enablesmulti-level fixation of vertebrae 170.

The pin plate 102 and the lock plate 104 may include a pin plateexterior face 182 and a lock plate exterior face 184, respectively (FIG.9). The pin plate exterior face 182 is positioned opposite of the pinplate interior surface 108 on the pin plate 102, and the lock plateexterior face 184 is positioned opposite of the lock plate interiorsurface 122 on the lock plate 104. The at least two compressor alignmentslots 185 may be disposed on opposite sides around the connector shaft128. Each of the exterior faces 182 and 184 may include at least twocompressor alignment slots 185 that extend partially into the exteriorfaces 182 and 184.

As shown in FIGS. 12-16, various tools may engage with the assembly 100and be utilized in use of the assembly 100. For example, as shown inFIG. 12, an embodiment of the assembly 100 can be associated with acombination inserter-compressor instrument 186. The combinationinserter-compressor instrument 186 is configured to simultaneouslyengage the at least two compressor slots 185 while inserting the lockpin 114 into the pin receptacle 112 and the threaded locking feature 158into the threaded channel 136 when the assembly 100 is positioned in asubject, such as a human, during spinal surgery.

As shown in FIG. 13, a single shaft inserter 188 may cooperate with theassembly 100 to insert the lock pin 114 into the pin receptacle 112.FIG. 14A illustrates a single locking tool 190 to insert the threadedlocking feature 158 into the threaded channel 136, being used with thesingle shaft inserter 188 while the assembly 100 is in-use during aspinal surgical procedure, such as a ligament sparing technique. In FIG.14A, the pin plate 102 is through a ligament 198, and the lock plate 104and the pivoting lock mechanism 126 are being introduced into thesurgical site. FIG. 14B is an enlarged view of the assembly 100 of FIG.14A.

FIG. 15 illustrates the single shaft inserter 188 and the single lockingtool 190 when using the ligament sparing technique. FIG. 16 illustratesthe assembly 100 being assembled and compressed using a pair of simplecompressors 192 in a spine 172.

In an embodiment, a kit is provided that includes the assembly 100. Thekit may include the lock pin 114, the pin plate 102, the lock plate 104,the pivoting lock mechanism 126, and the connector shaft 128. The kitmay include the threaded locking feature 158, the pivoting lock 142, andthe lock flange 148. At least one instrument may be provided in the kit,the instrument selected from the group of: the combinationinserter-compressor instrument 186, the single shaft inserter 188, thesingle locking tool 190, the simple compressor 192, and combinationsthereof.

A method of implanting and facilitating fixation between two spinalvertebrae is provided using the assembly 100 is provided. A posteriormidline skin and muscle incision is made between two spinous processes194 and is opened to the spinal vertebrae 170. A decompression isperformed, and/or an interbody device (not shown) is placed in anintervertebral disc space 196, and the assembly 100 is placed on thelateral sides of adjacent spinous processes 194 at the treated level,ensuring the pluralities of spikes 110 and 124 on medial facing plates102 and 104 are engaging bone. The plates 102 and 104 are compressedtoward each other, and the pluralities of spikes 110 and 124 are pressedinto the spinous processes 194. The lock plate 104 is then locked downusing the pivoting lock mechanism 126. FIGS. 6, 7, and 8 illustrate theassembly 100 locked onto the spine 172.

Spinal fusion surgical procedures using the disclosed spinous processplate fixation assembly 100 are referred to as ligament sparing typeprocedures. Advantageously, because the present assembly 100 isseparable and is able to be assembled in-situ, as shown in FIGS. 14A,14B, and 15, the ligament 198 does not need to be removed to use theassembly 100, enabling the present assembly 100 optimal for lessinvasive surgical procedures than alternative procedures and devices.During a ligament sparing procedure using the presently disclosedassembly 100, the pin plate 102 is inserted to the spine 172 and alignedto the first lateral side of two adjacent spinous processes 194. Thelock plate 104 is inserted to the spine 172 and aligned to the oppositelateral side of the two adjacent spinous processes 194. The plates 102and 104 are then moved toward each other such that the connector shaft128 is inserted through the second central aperture 120 in the lockplate 104 and into the pivoting lock 142. Upon engagement, the plates102 and 104 are urged toward each other until the pluralities of spikes110 and 124 are driven into the lateral sides of the adjacent spinousprocesses 194. The plates 102 and 104 are urged toward each other untila predetermined level of compression is reached, then the threadedlocking feature 158 is engaged to secure the assembly 100 in the fixedposition. The threaded locking feature 158 may be engaged, for example,by inserting it into the threaded channel 136 and rotating it so thatthe threads of the locking feature 158 and the channel 136 cooperate todrive the locking feature 158 into the channel 136. The instrumentsdisclosed herewith allow separation and assembly through theinterspinous ligament 198 without having to remove the ligament 198.

The assembly 100 may be constructed of any suitable materials, includingbiocompatible materials. Some embodiments of the assembly 100 areconstructed of non-absorbable biocompatible materials. Specific examplesof such suitable materials include titanium, alloys of titanium, steel,stainless steel, and surgical steel. The assembly 100, or parts thereof,could conceivably be made from non-metallic biocompatible materials,which include aluminum oxide, calcium oxide, calcium phosphate,hydroxyapatite, zirconium oxide, and polymers such as polypropylene. Theplates 102 and 104 and respective pluralities of spikes 110 and 124 maybe integrally formed.

Midline Spinous Process Allograft

As discussed above, the spinous process plate fixation assembly 100 canbe used with an allograft, such as a midline spinous process allograft.A midline spinous process allograft 200 is provided herein. Whenposterior fixation is performed, such as posterior lumbar fusion orposterior lumbar interbody fusion, a postlateral fusion typicallyextends to the transverse process in order to lay allograft or autograftto create a fusion. However, the allograft 200 of the present disclosureallows for the creation of a fusion without extending past the facets,enabling a less invasive surgical procedure compared to alternatives.

As shown in FIGS. 17 and 18, the allograft 200 is configured to bepositioned between spinous processes 202 of lumbar and/or thoracicvertebrae 204 during a spinal fusion surgical procedure. As shown inFIG. 18, the allograft 200 can be used in conjunction with pedicle screwsystems 206. The midline spinal allograft includes a body 208 having alower side (i.e., distal side) 210 opposite of an upper side 212 (i.e.,proximal side). The lower side 210 has a caudal groove 214 dimensionedto receive a cranial side of the lower spinous process 202. The upperside 212 has a cranial groove 216 dimensioned to receive a caudal sideof the upper spinous process 202. The cranial groove 216 may have acranial groove height 218 greater than a caudal groove height 220 of thecaudal groove 214. The cranial groove 216 may have a cranial groovewidth 222 greater than a caudal groove width 224 of the caudal groove214. The larger cranial groove 216 allows the allograft 200 to reach thelamina of the vertebra 204 of the spinous process 202, allowing formore, or enhanced, fusion. As shown in FIG. 17, the allograft 200 ispositioned for an L2 to L3 vertebrae 204 fusion.

The midline spinal process allograft 200 includes two lateral wings 226,each wing 226 disposed on opposite sides of the body 208. At least twolower legs 228 are disposed around the caudal groove 214, and at leasttwo upper legs 230 are disposed around the cranial groove 216. The lowerlegs 228 and upper legs 230 are disposed on opposite sides of the body208 and are proximate to the wings 226. The lower legs 228 may taperinwardly toward the caudal groove 214 such that each of the legs 228 hasa lower leg surface 250 shaped complementary to laminar for improvedlaminar contact.

The lateral wings 226 may be dimensioned to extend a distance that isfurther from the body 208 than a distance that the lower legs 228extend, as shown in FIG. 20. In an alternate embodiment, shown in FIG.19, the lateral wings 226 may be dimensioned to extend a distance thatis proximal from the body 208 than a distance that the lower legs 228extend. Advantageously, in embodiments of the allograft 200 havinglateral wings 226 that extend a distance that is further from the body208 than a distance that the lower legs 228 extend, the wider wings 226are capable of extending to a facet joint 248 of the vertebrae 204,allowing an increased amount of scaffold to incorporate a bone fusion.Moreover, wider wings 226 allow the wings to go more anterior to allowrod passage of the rod 240 above the allograft 200.

In an embodiment of the midline spinal process allograft 200, thecranial groove 216 continuously tapers inwardly away from the upper legs230 and toward a center 232 of the body 208. Similarly, the caudalgroove 214 may continuously taper inwardly away from the lower legs 228and toward the center 232 of the body 208.

The midline spinal process allograft 200 may have at least two caudalbone fixator spaces 234 dimensioned to receive a caudal bone fixator,such as the pedicle screw system 206. Each of the at least two caudalbone fixator spaces 234 is defined by the area between the lower legs228 and the lateral wings 226. In an embodiment of the midline spinalallograft 200, the allograft 200 may be vertically symmetrical around acenter plane 236.

The body 208 includes a top face 238 and lateral sides 244, the top face238 and lateral sides 244 each forming a junction 242 dimensioned toreceive a rod 240, such as the rod 240 of the pedicle screw system 206,shown in FIG. 18, positioned parallel to the junction 242. The junctions242 may continuously curve from the top face 238 to the lateral sides244 such that the junctions 242 are shaped complementary to the rod 240.

The allograft 200 may include a distal face 246 that continuously curvesinwardly away from the lateral sides 244 and toward the center point 232of the body 208. The distal face 246 may be dimensioned and shaped forspinal dura clearance after decompression of a spine 172 when theallograft 100 is in use in a subject. The shape and dimensions of theallograft 200, including the grooves 214 and 216 and the legs 228 and230, allows enhanced compression to occur between the vertebrae.

The allograft 200 may be fully demineralized or partially demineralized,or used without any demineralization. The allograft 200 may bedimensioned to fit several different anatomies, such as that of anadult, child, male, or female human. In embodiments of the allograft 200that are demineralized, the allograft 200 may fit a larger range ofsubject sizes that that of a mineralized allograft, increasing surgeonconvenience and technique. A kit may be provided having a plurality ofallografts 200, each having varying sizes so that a surgeon may selectthe optimal patient-specific allograft 200.

In yet another aspect, a method of producing a demineralized midlinespinous allograft, such as the allograft 200 of the present disclosure,is disclosed herein. The method includes harvesting cancellous bone,cutting the harvested cancellous bone into a predetermined block size,weighing the cut cancellous bone, determining the cut cancellous bonehas a mass density greater than a minimum mass density, shaping andsizing the cut cancellous bone to a predetermined shape and size to forma midline spinous allograft, washing the midline spinous allograft,demineralizing the midline spinous allograft in an acid, cleaning thedemineralized midline spinous allograft, and packaging the cleaneddemineralized midline spinous allograft. The packaging may includefreezing drying or packaging in saline. In embodiments having packagingin saline, the graft is dried, and bone marrow aspirate is taken from apatient and soaked into the demineralized allograft.

The harvesting may from a source of cancellous bone such as a condyle ofa femur bone of a human. The cancellous bone may be shaped with a manualmachine, such as a hand router, or a computer-controlled cuttingmachine. The minimum mass density may be about 0.8 g/cm³. The acid maybe hydrochloric acid. A plurality of demineralized midline spinousallografts using the method of demineralization disclosed herein. Theplurality of demineralized would be produced having differentpredetermined shapes and sizes such that a surgeon can select a patientspecific midline spinous allograft from the plurality of demineralizedmidline spinous allografts for use during spinal surgery of the patient.

It is to be understood that any given elements of the disclosedembodiments of the invention may be embodied in a single structure, asingle step, a single substance, or the like. Similarly, a given elementof the disclosed embodiment may be embodied in multiple structures,steps, substances, or the like.

The foregoing description illustrates and describes the processes,machines, manufactures, compositions of matter, and other teachings ofthe present disclosure. Additionally, the disclosure shows and describesonly certain embodiments of the processes, machines, manufactures,compositions of matter, and other teachings disclosed, but, as mentionedabove, it is to be understood that the teachings of the presentdisclosure are capable of use in various other combinations,modifications, and environments and are capable of changes ormodifications within the scope of the teachings as expressed herein,commensurate with the skill and/or knowledge of a person having ordinaryskill in the relevant art. The embodiments described hereinabove arefurther intended to explain certain best modes known of practicing theprocesses, machines, manufactures, compositions of matter, and otherteachings of the present disclosure and to enable others skilled in theart to utilize the teachings of the present disclosure in such, orother, embodiments and with the various modifications required by theparticular applications or uses. Accordingly, the processes, machines,manufactures, compositions of matter, and other teachings of the presentdisclosure are not intended to limit the exact embodiments and examplesdisclosed herein. Any section headings herein are provided only forconsistency with the suggestions of 37 C.F.R. § 1.77 or otherwise toprovide organizational queues. These headings shall not limit orcharacterize the invention(s) set forth herein.

The following is claimed:
 1. A spinous process plate fixation assembly,comprising: a pin plate including a first central aperture and a pinplate interior surface, and a first plurality of spikes extending fromthe pin plate interior surface; a lock plate including second centralaperture and a lock plate interior surface opposing the pin plateinterior surface, and a second plurality of spikes extending from thelock plate interior surface; a pin receptacle disposed within the pinplate, the pin receptacle configured to receive a lock pin; a pivotinglock mechanism disposed within the lock plate, wherein the pivoting lockmechanism includes: a threaded channel disposed within a top surface ofthe lock plate; a lock chamber disposed within the lock plate; apivoting lock disposed within the lock chamber and including a lock slotin communication with the threated channel , wherein the pivoting lockincludes a connector shaft passage configured to receive the lock sideof the connector shaft, wherein the pivoting lock includes a compressionslot proximal to the lock slot and opposite from a compression flatconfigures for orientation when the pivoting lock is compressed; and aconnector shaft extending from the pin plate to the lock plate andpassing through the first central aperture and the second centralaperture, the connector shaft including: a pin side configured toreceive the lock so as to secure the pin within the pin receptacle; anda lock side opposite the pin side, the lock side configured tooperatively engage the pivoting lock mechanism so as to pivotally securethe lock side with the pivoting lock mechanism.
 2. The spinous processplate fixation assembly of claim 1, further comprising a lock flangeconfigured to secure the pivoting lock within the lock chamber.
 3. Thespinous process plate fixation assembly of claim 1, wherein the pivotinglock includes an exterior toroidal surface and an interior friction fitsurface.
 4. The spinous process plate fixation assembly of claim 1,wherein the compression slot is configured to be reduced when thepivoting lock is compressed.
 5. The spinous process plate fixationassembly of claim 1, wherein each of the first plurality of spikes andthe second plurality of spikes include spikes having cuboid-shaped basesand pyramid-shaped tips.
 6. The spinous process plate fixation assemblyof claim 1, wherein each of the pin plate and the lock plate include atleast two offset flat portions including the first plurality of spikesand the second plurality of spikes, respectively.
 7. The spinous processplate fixation assembly of claim 1, wherein each of the first pluralityof spikes and the second plurality of spokes include minor spikes andmajor spikes.
 8. The spinous process plate fixation assembly of claim 1,each of the pin plate and the lock plate include at least two staggeredflat portions.
 9. The spinous process plate fixation assembly of claim1, wherein each of the pin plate and the lock plate include an exteriorface opposite of the pin plate interior surface and the lock plateinterior surface, respectively, and each of the exterior faces includeat least two compressor alignment slots disposed on opposite sides ofthe connector shaft.
 10. A spinous process plate fixation assembly,comprising: a pin plate comprising a pin plate interior surface, and afirst plurality of spikes extending from the pin plate interior surface;a lock plate including a lock plate aperture and a lock plate interiorsurface opposing the pin plate interior surface, and a second pluralityof spikes extending from the lock plate interior surface; a pivotinglock mechanism disposed within the lock plate, wherein the pivoting lockmechanism includes: a threaded channel disposed within a top surface ofthe lock plate; a lock chamber disposed within the lock plate; apivoting lock disposed within the lock chamber and including a lock slotin communication with the threaded channel, wherein the pivoting lockincludes a connector shaft passage configured to receive the lock sideof the connector shaft, wherein the pivoting lock includes a compressionslot proximal to the lock slot and opposite from a compression flatconfigured for orientation when the pivoting lock is compressed; and aconnector shaft extending from the pin plate to the lock plate andpassing through the lock plate aperture, the connector shaft including:a pin side secured to the pin plate; and a lock side opposite the pinside, the lock side configured to operatively engage the pivoting lockmechanism so as to pivotally secure the lock side with the pivoting lockmechanism.
 11. The spinous process plate fixation assembly of claim 10,further comprising a lock flange configured to secure the pivoting lockwithin the lock chamber.
 12. The spinous process plate fixation assemblyof claim 10, wherein the pivoting lock includes an exterior toroidalsurface and an interior friction fit surface.
 13. The spinous processplate fixation assembly of claim 10, wherein the compression slot isconfigured to be reduced when the pivoting lock is compressed.
 14. Thespinous process plate fixation assembly of claim 10, wherein each of thefirst plurality of spikes and the second plurality of spikes includespikes having cuboid-shaped bases and pyramid-shaped tips.
 15. Thespinous process plate fixation assembly of claim 10, wherein each of thepin plate and the lock plate include at least two offset flat portionsincluding the first plurality of spikes and the second plurality ofspikes, respectively.
 16. The spinous process plate fixation assembly ofclaim 10, wherein each of the first plurality of spikes and the secondplurality of spokes include minor spikes and major spikes.
 17. Thespinous process plate fixation assembly of claim 10, each of the pinplate and the lock plate include at least two staggered flat portions.18. The spinous process plate fixation assembly of claim 10, whereineach of the pin plate and the lock plate include an exterior faceopposite of the pin plate interior surface and the lock plate interiorsurface, respectively, and each of the exterior faces include at leasttwo compressor alignment slots disposed on opposite sides of theconnector shaft.
 19. The spinous process plate fixation assembly ofclaim 10, wherein the pin plate comprises a pin plate aperture, and theconnector shaft passes within the pin plate aperture.
 20. The spinousprocess plate fixation assembly of claim 19, wherein the pin platecomprises a pin receptacle disposed within the pin plate, the pinreceptacle configured to receive a lock pin, wherein the pin side of theconnector shaft is configured to receive the lock pin so as to securethe pin side within the pin receptacle.